someone messed up my cam sprocket chains!

[josephb983]

Hey, I took valve cover off, and it looks like the cam sprockets are not aligned. They are 1 tooth off from each other, so if you turn one straight up (arrow up on end of cam shaft), other end is at an angle about equivalent to 1 tooth of the sprocket.

How can I find top dead center on my 1991 318is M42? How can I know which cam sprocket is off by one tooth? How can I be sure it really is off one tooth like I think?

The problem is the chain was replaced, and the car makes horrible noises at 4k rpm and above. Exactly the symptoms I have heard can be caused when the timing was way off. I do not know who did the work on this engine, or I'd talk to them.

[Cristian G in Oz]

There are a number of simple ways to find TDC.

to check the engine is at TDC, remove the spark plugs (it's easier to wind over) and wind the car over by hand. Use a 22mm socket on the crank bolt.
Ensure you only turn the engine clockwise as you look at it from the front, ie if you have a ratchet on the crank nut push it from vertical down to the side with the alternator on it.
Now look at the cams as your turning the car over.
When the lobes on the inlet and exhaust cam point up towards each other evenly, your engine should be at TDC.

Now check the arrows on the cam gears, they should both be pointing at the top of the engine, not pointing up vertically.

Since you have the rocker cover off now have a look at the back of the cams at the back of the head.  There should be a "square" bit right at the end of the cam. When you place a straight edge/steel rule across them the flat bits should match the side of the rule.
This ensures your cams are timed together.

There are a couple of other things you can do as well but this will be the quickest and easiest.

Good luck. Let us know how you get on.

[josephb983]

One of them is off, not pointing as it should. However, I can turn the engine a bit more then the other one is off instead. How can I tell if it is the intake or exhaust cam that is set one tooth off?

I had thought that if there were a way to look at the markings on the engine (if there are such?) that I could set it true TDC and then look to see which cam is not pointing as it is supposed to. Is this possible with this engine?

[txleadfoot]

Here are some photos at TDC, locked in place by a cam lock tool.

Check out the arrow on the block (I painted red).  That should line up with a tick mark on your harmonic balancer at TDC as well.  What you can't see is a flywheel lock tool that locks at TDC.

So theoretically, the cam lock, flywheel lock, and harmonic balancer should all be in TDC position at the same time.  You may have to rotate the engine by hand a few times to get everything in sync.

[josephb983]

I found the arrow, however I can't find the tick mark on the harmonic balancer. What does it look like?

I also could not find the hole the book talks about for aligning with the flywheel... where is this hole? Is it on the side by the alternator, or the other side?

[nicknikolovski]

Stand in front of the engine, now go to air filter side. Look down past the intake manifold and find your starter motor. The flywheel pin hole is just below the starter in a special grooved area on the bellhousing. Line up the crankshaft first. Once the crank is set and locked at tdc using the flywheel pin, then you can adjust the cams.

If you are not confident enough to attempt the following procedure I recommend taking the vehicle to a garage - DO NOT drive the vehicle with the timing out. The chain could skip another tooth and bend valves.

With the valve cover off (yours is already off), remove the tensioner piston completely.
Then once there is slack in the chain, I would unbolt the camshaft sprockets and remove them. Move the top section of the chain out with them. Then if the exhaust camshaft is set correctly at TDC on cyl 1, you will only need to adjust the intake cam or vice versa. Obviously with chain off the camshafts, they become independent in their movement with opening or closing valves. So if you need to adjust the intake cam, you will need to turn it in the direction it requires to go until both the cam lobes at cyl 1 point toward each other and the end of the cams are parallel with the head like in the above picture. Once you have this corrected, put your cam locking tool on. This verifies that you crank and now your cams are at TDC. Put your chain back on over your cam sprockets and position the cam sprockets back onto the camshafts with the each of the 4x bolts in about the central position in the elongated slots and with the arrows pointing correctly. Once everything is ok, re-install the compressed tensioner piston to tension the chain. Check that you have 14 rivets on the chain running along between the arrows on the cam sprockets. For reference here is a picture:
http://www.esatclear.ie/~bpurcell/camgearmark.jpg

If this is ok, then remove your cam locking tool and flywheel pin and rotate the crankshaft at least 2 revolutions and then bring the engine to TDC again, insert the flywheel pin again and see if your cam locking tool sits parallel with the head and over the square ends on the camshafts. If this OK, then you have just corrected your problem. If the timing is still out repeat until you get it correct. Good luck

[nicknikolovski]

How did you go?

[RED IS 91]

Stand in front of the engine, now go to air filter side. Look down past the intake manifold and find your starter motor. The flywheel pin hole is just below the starter in a special grooved area on the bellhousing. Line up the crankshaft first. Once the crank is set and locked at tdc using the flywheel pin, then you can adjust the cams.

If you are not confident enough to attempt the following procedure I recommend taking the vehicle to a garage - DO NOT drive the vehicle with the timing out. The chain could skip another tooth and bend valves.

With the valve cover off (yours is already off), remove the tensioner piston completely.
Then once there is slack in the chain, I would unbolt the camshaft sprockets and remove them. Move the top section of the chain out with them. Then if the exhaust camshaft is set correctly at TDC on cyl 1, you will only need to adjust the intake cam or vice versa. Obviously with chain off the camshafts, they become independent in their movement with opening or closing valves. So if you need to adjust the intake cam, you will need to turn it in the direction it requires to go until both the cam lobes at cyl 1 point toward each other and the end of the cams are parallel with the head like in the above picture. Once you have this corrected, put your cam locking tool on. This verifies that you crank and now your cams are at TDC. Put your chain back on over your cam sprockets and position the cam sprockets back onto the camshafts with the each of the 4x bolts in about the central position in the elongated slots and with the arrows pointing correctly. Once everything is ok, re-install the compressed tensioner piston to tension the chain. Check that you have 15 rivets on the chain running along between the arrows on the cam sprockets. For reference here is a picture:
http://www.esatclear.ie/~bpurcell/camgearmark.jpg

If this is ok, then remove your cam locking tool and flywheel pin and rotate the crankshaft at least 2 revolutions and then bring the engine to TDC again, insert the flywheel pin again and see if your cam locking tool sits parallel with the head and over the square ends on the camshafts. If this OK, then you have just corrected your problem. If the timing is still out repeat until you get it correct. Good luck

Check that you have 15 rivets on the chain running along between the arrows on the cam sprockets. For reference here is a picture:
http://www.esatclear.ie/~bpurcell/camgearmark.jpg

How come I only count 14

[nicknikolovski]

Oh sorry, my honest mistake.

[RED IS 91]

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f**king spammer ...........................

[nicknikolovski]

who is? and how do you know?